Light-emitting devices such as lasers are useful for optical signal generation in optoelectronic networks. Often, light from a laser is modulated to encode data or information onto the signal. One approach to modulating laser light is electro-absorption modulation (EAM), in which an electric potential applied across the modulator either allows light to pass through the modulator or creates a destructive interference pattern in the light passing into the modulator, thereby turning the light signal off.
To reduce power consumption, the electro-absorption modulated laser (EML) can be modulated differentially. Differential modulation using electro-absorption modulators has either used discrete laser and modulator devices, or, if integrated on a single chip, the modulator section and the laser section generally have common electrical inputs (e.g., contacts). The common electrical inputs typically include the cathode, n-contact(s), and/or ground. The anodes or p-contacts of the laser section and modulator section may be electrically isolated.
However, in a multi-channel transmitter (i.e., having a plurality of paired lasers and modulators), providing a common ground contact for the modulators does not allow for driving each modulator with a differential signal. Thus, a need exists for a multi-channel transmitter in which the modulators for the different channels have input and output contacts that are electrically isolated from each other.
This “Discussion of the Background” section is provided for background information only. The statements in this “Discussion of the Background” are not an admission that the subject matter disclosed in this “Discussion of the Background” section constitutes prior art to the present disclosure, and no part of this “Discussion of the Background” section may be used as an admission that any part of this application, including this “Discussion of the Background” section, constitutes prior art to the present disclosure.